1. Field of the invention
The present invention concerns a device for the angular positioning of a limb of a patient resting on an operating table or a treatment table.
It applies in particular, but not exclusively, to the positioning of a leg of a patient during a knee operation.
2. Description of the prior art
In general terms, it is known that, in order to perform such positioning, there has already been proposed a support device involving a cylinder whereof the rod supports a spindle that extends transversely to the cylinder rod and carries a cradle intended to support the leg of the patient. This arrangement of the various members causes the occurrence of a large lateral torque formed by the weight of the supported leg and the length of the spindle carrying the cradle. This torque, being applied in full to the head of the cylinder and its rod, quickly leads to deterioration and malfunctioning thereof. Moreover, through its position, this type of bar hinders the surgeon in the accomplishment of his actions and makes difficult the possible concomitant use of devices that could prove useful.
There has also been proposed an appliance comprising a cradle-support bar attached to the end of a crank coupled to the rod of a cylinder by means of an articulation so that the translational movement of the cylinder rod creates a rotational movement of the cradle-support bar. This solution is not satisfactory given that the appliance described is mounted on a lateral edge of the operating table and that consequently the pelvis of the patient has a tendency to tilt causing a movement of the knee which does not take place in a vertical plane parallel to the longitudinal axis of the operating table. This results in inaccuracy on the verticality of the leg and on the surgical operation on the knee.
There has furthermore been proposed a device for adjusting the angular position of a limb of a patient resting on an operating table comprising:                a shelf provided on two opposite lateral edges with means of fixing with adjustable spacing onto the two lateral guide rails of an operating table; and        a trough support mounted by one of its ends on a rotary transverse shaft carried by the shelf and driven rotationally by a drive mechanism by means of a link enabling a translational movement of the trough support whilst allowing its rotational driving by said shaft.        
This solution is not satisfactory given that the pelvis of the patient has a tendency to tilt causing a movement of the knee which does not take place in a vertical plane parallel to the longitudinal axis of the operating table.